Color error corrected segmented led array

ABSTRACT

A method of color error correction for a segmented LED array is disclosed. The method includes calculating a target luminance for LED segments in a segmented LED array based on an initial luminance pattern, determining a luminance ratio based on the target luminance, the luminance ratio defined as a ratio of a primary luminance value of the primary LED segment to a secondary luminance value of the at least one adjacent LED segment, and comparing the luminance ratio to a predefined threshold ratio. If the luminance ratio is greater than or equal to the predefined ratio, then the secondary luminance value of the at least one adjacent LED segment is maintained. If the luminance ratio is less than the predefined ratio, then the secondary luminance value of the at least one adjacent LED segment is increased.

FIELD OF INVENTION

The present invention generally relates to light emitting diodes (LEDs),and more particularly relates to color error correction for an array ofLEDs.

BACKGROUND

In photography, camera flashes from an LED array can cause undesirablecolor temperature disruptions. Conventional camera flash systems withcolor adjustable flash units are known. For example, U.S. Pat. No.8,817,128, which is incorporated by reference, discloses adjustingillumination for controlling color temperature in a camera flash system.Data that corresponds to the ambient light of a physical environment iscollected, such as by a color temperature meter included in the camera.The ambient light has a distribution of color temperatures that cycleover a fixed time period. When a flash request is received, a time cycleis calculated to determine when the flash unit will flash. A colortemperature is identified from a distribution of color temperatures, anda color temperature is predicted for ambient light that is present inthe physical environment when the flash unit flashes. The colortemperature of the flash unit is then set to the identified colortemperature.

Color temperature selection for an array of LEDs is also known. Forexample, U.S. Pub. 2005/0168965, which is incorporated by reference,describes an array of LEDs used in a flash device. In this disclosure,light flashes towards a subject in a photographic scene using an LEDmatrix array, such that individual lighting fields differ from oneanother. A selective excitation circuit is used for selectivelyilluminating the LEDs so as to produce a projected flash light, whichdiffers in intensity.

Segmented LED arrays with adaptive flash features are also known. TheseLED arrays allow flash systems to illuminate a scene more homogenously,without uneven bright and dark regions. Adaptive flash LEDs can be usedto avoid overexposure by selective dimming and/or enhancing of certainLED segments within the LED array. To ensure satisfactory contrast in ascene illumination, optics can effectively image the LED array onto aselected scene. However, for white LEDs, color variations still existdue to local over-conversion of light. This over-conversion can produceyellow light due to locally thicker phosphor layers in the LED array. Insegmented LEDs, during selective illumination a single LED of the LEDarray is illuminated while a directly adjacent or neighboring LED is notilluminated. In monolithic matrix LED arrays, a sapphire or phosphorlayer covers the active light emission sites as a single piece or layer.This arrangement leads to light deflecting inside the matrix blocks. Dueto different extraction efficiencies (i.e. how much blue or phosphorconverted light is projected from the LED), a single illuminated LEDsegment may generally cause a yellow rim in adjacent switched off LEDsegments.

It would be desirable to provide an LED array that reduces or eliminatesthe undesirable color error in an LED array.

SUMMARY

Briefly stated, an improved LED array system is provided thatselectively illuminates neighboring LED segments surrounding a primaryilluminated LED segment to effectively reduce color errors thatotherwise occur in closely packed LED arrays.

In one embodiment, a method for correcting color errors in an LED arraysystem is provided that selectively illuminates neighboring LED segmentsaround a primary illuminated LED segment. Selective illumination ofneighboring LED segments around a primary illuminated LED segmentcorrects color errors that are otherwise introduced by the neighboringLED segments due to over-converted light and leaked light within the LEDarray.

Illumination of the neighboring LED segments is relatively low. Forexample, in one embodiment the illumination of the neighboring LEDsegments is less than 10% of the illumination of the primary illuminatedLED segment, such that contrast between the LED segments is notdiminished or negatively impacted. The illumination level of theneighboring LED segments is calibrated based on physical characteristicsof the LED array, such as die structure, layer thickness, layercomposition, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing Summary as well as the following Detailed Description willbe best understood when read in conjunction with the appended drawings.In the drawings:

FIG. 1 is a side view of a segmented LED array.

FIG. 2 is a side view of a segmented LED array with a specific LEDsegment illuminated.

FIG. 3 is a graph of power versus wavelength for a typical LED array.

FIG. 4 is a top view of a segmented LED array with a single LED segmentilluminated.

FIG. 5 is a top view of a segmented LED array with a primary LED segmentilluminated and neighboring LED segments selectively illuminatedaccording to one embodiment.

FIG. 6 is a schematic drawing of an LED array system according to oneembodiment.

FIG. 7 is a flow chart of a method for color error correction for asegmented LED array according to one embodiment.

FIG. 8 is a graph showing a luminance threshold versus a relativeluminance value for an LED array.

FIG. 9 is a graph showing color variation and contrast at varyingneighbor relative flux values.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that the figures and descriptions for an LEDarray system and method of correcting color error for an LED arraysystem have been simplified to illustrate elements that are relevant fora clear understanding, while eliminating, for the purpose of clarity,many other elements found in typical electronics packaging. Those ofordinary skill in the art may recognize that other elements and/or stepsare desirable and/or required in implementing the present invention.However, because such elements and steps are well known in the art, andbecause they do not facilitate a better understanding of the presentinvention, a discussion of such elements and steps is not providedherein.

FIGS. 1 and 2 illustrate LED arrays 10, 20 including a die layer 12, 22,a sapphire layer 14, 24, and a phosphor layer 16, 26. One of ordinaryskill in the art would recognize that alternative materials for the LEDarray 10, 20 can be used. As shown schematically in FIG. 2, blue light(indicated by the two arrow lines traveling in a straight path) does notpropagate very far in the phosphor layer 26 since the probability to beconverted in the phosphor increases with the traveled path length.However, phosphor converted light can propagate in the phosphor layer26, as shown schematically in FIG. 2 by the multiple angled lines, whichcan cause undesirable color errors. Differences in the propagationcharacteristics of the layers result in a color variation over the LEDarray 10, 20. Characteristics of the LED array 10, 20, such as thicknessof the sapphire layer 14, 24, thickness of the phosphor layer 16, 26,adding layers to the LED array 10, 20, phosphor concentration, and othercharacteristics result in varying luminance and color characteristicsfor the LED arrays 10, 20. Due to these variations, LED arraysexperience undesirable color errors and variations, resulting in colorshading in a photographed scene. FIG. 3 is a graph showing exemplarycharacteristics of emitted spectral power density versus wavelength fora white LED, and shows the respective locations of the blue die (i.e.pump) and the yellowish spectrum of the phosphor converted light.

FIG. 4 illustrates one type of luminance pattern for an LED array 30.This luminance pattern corresponds to one type of adaptive flash.Adaptive flash selectively illuminates only those portions of the scenewhich need more illuminance compared to other areas which aresufficiently illuminated by ambient light. One such adaptive flashconfiguration is disclosed in WO 2017/080875, which is incorporated byreference as if fully set forth herein.

One of the ways to realize adaptive flash is to use an LED array under acommon lens. Segments of the LED array can be selectively switched onand will illuminate only a correlated part of the scene. In thisluminance pattern, a primary LED segment 32 is illuminated, while all ofthe neighboring secondary LED segments 34 a-34 h are not illuminated. Inthis luminance pattern, leaked light has a higher probability of causingan undesirable halo or rim effect around the single primary LED segment32.

FIG. 5 illustrates an embodiment of an LED array 40. As shown in FIG. 5,a primary LED segment 42 is illuminated. In this mode, directly adjacentsecondary LED segments 44 a-44 d are also illuminated, but to a muchlower degree than the primary LED segment 42. As used herein, the termdirectly adjacent secondary LED segment refers to an LED segment thatshares an entire sidewall with the primary LED segment. In a preferredembodiment, the directly adjacent secondary LED segments 44 a-44 d areilluminated at an illumination intensity “X.” This illuminationintensity is determined based on a compromise of color variation andcontrast.

In this embodiment, diagonally adjacent secondary LED segments 46 a-46 dare illuminated to a lower level than the directly adjacent secondaryLED segments 44 a-44 d. As used herein, the term diagonally adjacentsecondary LED segment refers to an LED segment that only contacts theprimary LED segment at a point or a corner. In one embodiment, thediagonally adjacent secondary LED segments 46 a-46 d are illuminated toan illumination intensity “X/2”, i.e. half of the intensity level of thedirectly adjacent secondary LED segments 44 a-44 d. One of ordinaryskill in the art would recognize from the present application that theintensity level of the diagonally adjacent secondary LED segments 46a-46 d can be more or less than X/2. For example, in one embodiment, theluminance value of the at least one diagonally adjacent LED segment isbetween 40-60% of the luminance value of the at least one directlyadjacent LED segment.

Although there is only a single primary LED segment illuminated in FIG.5, one of ordinary skill in the art would recognize that the concept ofselective relatively low illumination of neighboring LED segments can beused in a variety of illumination profiles. For example, there can bemultiple primary LED segments, each including adjacent secondary LEDsegments with relatively low-level illumination intensities.

FIG. 6 illustrates a system 100 for color error correction of an LEDarray. The system 100 includes a digital image capture device 110. Oneof ordinary skill in the art would recognize from the present disclosurethat the digital image capture device 110 can be a smartphone camera, avideo camera, a compact camera, a digital single lens reflex (“dSLR”)camera, or any other type of image capturing device.

In one embodiment, the device 110 includes a sensor 120, a CPU 130, andan LED array 160. In one embodiment, the sensor 120 is a user interface.In one embodiment, sensor 120 also includes a keyboard or a touchscreen.A user can select a specific setting for adaptive lighting by selectinga mode on a user interface. In an alternative embodiment, the sensor 120can include any type of optical sensor as understood by those ofordinary skill in the art. In one embodiment, the sensor 120 can convertoptical images into electrical signals representative of an intensityand luminance of ambient light captured by the sensor 120. The sensor120 can provide these signals to the CPU 130 for further processing andanalysis.

The LED array 160 can include any of the features described above withrespect to LED arrays. Although the LED array 160 is illustrated as a3×4 array in FIG. 6, one of ordinary skill in the art would recognizefrom the present disclosure that the size and configuration of the LEDarray 160 can be varied.

The CPU 130 preferably includes a processor 140 and a driver 150. Theprocessor 140 may be, for example and without limitation, amicroprocessor or a plurality of microprocessors, a single-core ormulti-core processor, a general purpose processor, a special purposeprocessor, a conventional processor, a Graphics Processing Unit (GPU), adigital signal processor (DSP), one or more microprocessors associatedwith a DSP core, a controller, a microcontroller, or any other any unit,module, or machine capable of executing a sequence of instructions. Thedriver 150 can include any known selective excitation/illuminationelements, such as a selective excitation circuit, excitation controlcircuit, power supply circuit, and input/output circuit disclosed inU.S. Pub. 2005/0168965, and specifically illustrated in FIG. 2 of U.S.Pub. 2005/0168965, which is incorporated by reference as if fully setforth herein. The driver 150 is configured to provide varying inputsignals to the LED array 160 to illuminate specific LED segments 162 ofthe LED array 160. The driver 150 is also configured to provide varyinginput signals to the LED array 160 regarding the illumination values ofthe specific LED segments 162 of the LED array 160. Varying luminancepatterns can be stored in the CPU 130 via a memory unit or other datastorage unit.

The sensor 120 is configured to detect a brightness profile and opticalcharacteristics of a scene. The brightness profile is representative ofrelative incident light in a specific scene. The CPU 130 receives inputfrom the sensor 120 regarding the brightness profile and characteristicsof the scene. The CPU 130 performs image processing and algorithms onthe input received from the sensor 120 regarding the brightness profileof the scene. Based on this information, the CPU 130 calculates a targetluminance for LED segments 162 in the LED array 160.

The CPU 130 is also provided with a predefined threshold ratio. Thepredefined threshold ratio is defined by a relative luminance of asingle LED segment in an LED array compared to a luminance of anadjacent LED segment. The predefined threshold ratio is selected basedon testing and data for a wide range of LED arrays. The predefinedthreshold ratio is selected to minimize color errors. FIGS. 8 and 9,which are discussed in more detail below, provide optical simulationdata regarding determining an optimal predefined threshold ratio.According to one embodiment, the predefined threshold ratio is at least3% and less than 5%. In a more preferred embodiment, the predefinedthreshold ratio is 4%.

The CPU 130 is provided with a predefined threshold ratio and uses thispredefined threshold ratio to determine if particular LED segments 162in the LED array 160 should be illuminated based on a comparison of adetected brightness profile to the predefined threshold ratio. The CPU130 regulates a current provided to each individual LED segment 162 inthe LED array 160. The driver 150 provides an input signal to the LEDarray 160 regarding which LED segments 162 are illuminated and therelative luminosity of each of the LED segments 162 in the LED array160.

In one embodiment, the CPU 130 is provided with the predefined thresholdratio from an external source, i.e. a source that is external from thedevice 110. For example, in one embodiment, a plurality of the CPUs areprogrammed during manufacturing after a specific type of LED array thatis representative of a plurality of LED arrays has been tested andcalibrated. Characteristics of the plurality of LED arrays are stored ina memory connected to a respective one of the plurality of CPUs.Characteristics for the LED array can be experimentally determined, andthen stored in memory, such that they can be utilized by the CPUs tocause the LED array to be driven with a specific predefined thresholdratio based on the characteristics of that specific LED array.

An input device 170 can encode or program the device 110 with a specificpredefined threshold ratio. In one embodiment, the predefined thresholdratio is unique to a specific LED array, a specific model of LED array,a specific lot of LED arrays, or other class or subset of LED arrays.One of ordinary skill in the art would recognize that thecharacteristics of an LED array are dependent upon die structure,thickness and content of layers within the LED array, and other factors.One of ordinary skill in the art would also recognize that optics and anacceptable color error in a scene may vary threshold ratios. Duringassembly of a plurality of the devices 110, a single predefinedthreshold ratio can be selected for a plurality of LED arrays 160 thatare being installed into a respective one of the plurality of thedevices 110. The input device 170 can then program or encode arespective one of the CPUs 130 in the devices 110 with the predefinedthreshold ratio.

In another embodiment, the device 110 can dynamically determine thepredefined threshold ratio. In one embodiment, the CPU 130 is providedwith an integrated input device 170 that is configured to determine thepredefined threshold ratio. The input device 170 in this embodimentdetermines the predefined threshold ratio in situ, i.e. while a user isoperating the device 110. In one embodiment, an algorithm determinescolor error experienced by each LED segment and iteratively addsintensity for neighboring LED segments. After the color error is lowenough according to a predetermined target, then the threshold isdetermined. This algorithm can be provided to users of multiple devicesor could be implemented during manufacturing of the devices.

In one embodiment, the dynamic determination of the predefined thresholdratio requires determining a color error experience by each LED segmentin an LED array, and iteratively toggling turning on neighboring LEDsegments. Once the color error is low enough, then the threshold isknown. This algorithm can be given to the user of the devices 110, orcould be performed as factory calibration.

A predefined luminance threshold can be tested for a specific LED arrayto determine an acceptable color error. FIG. 8 illustrates the colorerror for an illumination provided by a specific LED array with aprimary LED segment (p) being illuminated, as well as the color errorfor an illumination with neighboring LED segments illuminated. As shownin FIG. 8 in false color plots, a relatively acceptable color error isindicated by a blue (b) region, while a moderately acceptable colorerror is indicated by a green (g), and unacceptable color error isindicated by a red (r) region. The legend in FIG. 8 generally indicatesred for color error with values 0.095-0.1, orange for color error withvalues 0.085-0.09, yellow for color error with values 0.075-0.08, lightgreen for color error with values 0.055-0.06, green for color errorswith values 0.04-0.045, turquoise for error values 0.025-0.03, lightblue for color error with values 0.015-0.02, blue for color error withvalues 0.01-0.015, and dark blue for color errors with values 0-0.005.Intermediate shades of the colors are represented in the values notexplicitly identified herein. Several metrics can be used to definecolor errors. One such metric applied here is the color difference inu′, v′ space. In one embodiment, the color difference can be defined bythe following calculation:sqrt((u′-u′_(reference))²+(v′-v′_(reference))²) wherein u′, v′ are thecolor coordinates over the source in the color space (L*, u*, v*), andu′_(reference) and v′_(reference) are the targeted color point. Thesevalues are understood by those of ordinary skill in the art, asexplained by the International Commission on Illumination (CIE).

As shown in FIG. 8, for the 0% luminance threshold and 0% relativeluminance value of neighbor segments, a majority of the image is green(g), while an outer edge of the plot is red (r), and the primary LEDsegment (p) is blue (b). As the luminance threshold is increased on theY-axis to 1%, the relative size of the green (g) area decreases, and alarger portion of the plot is blue (b). As the luminance threshold isincreased to 5%, the majority of the plot is blue (b), and a smallerhalo of green (g) remains around the primary LED segment (p). Finally,as the luminance threshold is increased to 10%, there is only a smallgreen (g) halo forming a band around the primary LED segment (p), andthe vast majority of the plot is blue (b). This Figure shows that thehighest color errors are only present for small luminance in this case,but still present and visible for the attentive observer (i.e. the greenarea at the 0% luminance threshold). The present disclosure neutralizesthe color error by switching on the neighboring segment with lowcurrent. This effect is shown by the results along the X-axis. As therelative luminance value of neighbor segments is increased to 2%, apatch of green (g) is remains on the left side of the image, while agreen (g) circle around the primary LED segment (p) includes some blue(b) portions around its periphery. At a relative luminance of 4%, thegreen (g) band on the left hand side of the image remains, but the green(g) circle around the primary LED segment (p) disappears, and a majorityof the area surrounding the primary LED segment (p) is blue (b).Finally, at 8% relative luminance the green (g) band remains on the leftside of the image and the blue (b) around the primary LED segment (p)has turned from a light blue to a light blue-green. As shown by FIG. 8,the 4% relative luminance has the lowest overall color error. Therelative values of the luminance can be varied based on the data fromthe graph in FIG. 8. One of ordinary skill in the art recognizes thatthis graph is for one type of LED array with a specific luminancepattern. Alternative graphs can be generated for other types of LEDarrays and luminance patterns, which will vary based on characteristicsof the LED array structure.

FIG. 9 illustrates a graph of the color variation and contrast of animage based on a varying neighbor relative flux value. The neighborrelative flux value corresponds to luminance ratio as used herein.Neighbor relative flux compares the luminance value of one LED segmentof an LED array versus the luminance value of a second neighboring LEDsegment of the LED array. As shown in FIG. 9, at 0% neighbor relativeflux, the color variation is between 0.072-0.075 and the contrast isaround 92%-94%. As the neighbor relative flux increases to 2%, the colorvariation drops to around 0.050-0.052, and the contrast drops to around88%. When the neighbor relative flux increases to 4%, the colorvariation continues to drop, but at a lower rate to around 0.045-0.047,and the contrast steadily decreases to around 85%. When the neighborflux increases to 6%, the color variation begins to increase to around0.048-0.050 and the contrast decreases to around 81%. Finally, at 8%neighbor relative flux, the color variation increases to around0.056-0.058 and the contrast decreases to around 77%-78%. As shown byFIG. 9, while the color error is reduced by powering the neighborsegments, the contrast decreases. As shown in FIG. 8, the color errorshows a minimum at 4%, while the contrast ratio decreases continuously.Depending on the specific weight factor that a particular applicationassigns to the contrast ratio or color error, the best relative flux forthe neighbors can be chosen.

In one embodiment, referring to FIG. 7, a method 200 of color errorcorrection for a segmented LED array is provided. According to themethod 200, an initial illuminance pattern is measured or captured 210.This step generally requires taking a photo. The photo then is used as abrightness profile of a scene. Areas within the scene with brightnesslevels below the targeted brightness of the picture are filled in by theadaptive flash brightness profile. In one embodiment, this profile maybe the inverse of the existing picture brightness (i.e. to the extentpossible based on the available flux from the flash). Next, a targetluminance per LED segment of a segmented LED array is calculated 220,which corresponds to the aforementioned target brightness profile in thescene to be generated. This value is determined according to an adaptiveflash algorithm, as described herein.

The method 200 includes determining a luminance ratio 230 betweenadjacent LED segments of the segmented LED array. The luminance ratio isdefined as a ratio of a primary luminance value of the primary LEDsegment compared to a secondary luminance value of the at least oneadjacent LED segment. The method 200 includes comparing the luminanceratio to a predefined threshold ratio 240. Based on the outcome of thiscomparison, the luminance of the at least one adjacent LED segment iseither maintained 250 or changed 260. In a preferred embodiment, theluminance of the at least one adjacent LED segment is either maintainedor increased. If the luminance ratio is greater than or equal to thepredefined ratio, then the secondary luminance value of the at least oneadjacent LED segment is maintained 250. If the luminance ratio is lessthan the predefined ratio, then the secondary luminance value of the atleast one adjacent LED segment is increased 260. In one embodiment, thesecondary luminance value of the at least one adjacent LED segment isincreased until the luminance ratio equals the predefined thresholdratio.

The non-limiting methods and embodiments described herein for an LEDarray system and a method of correcting color error for an LED arraysystem may be modified for a variety of applications and uses whileremaining within the spirit and scope of the claims The implementationsand variations described herein, and/or shown in the drawings, arepresented by way of example only and are not limiting as to the scopeand spirit. The descriptions herein may be applicable to allimplementations of the method and system described herein although itmay be described with respect to a particular implementation.

As described herein, the methods described herein are not limited to anyparticular element(s) that perform(s) any particular function(s) andsome steps of the methods presented need not necessarily occur in theorder shown. For example, in some cases two or more method steps mayoccur in a different order or simultaneously. In addition, some steps ofthe described methods may be optional (even if not explicitly stated tobe optional) and, therefore, may be omitted. These and other variationsof the methods disclosed herein will be readily apparent, especially inview of the description of the method for using sputtering deposition togrow layers in light emitting devices described herein, and areconsidered to be within the full scope of the invention.

Some features of some implementations may be omitted or implemented withother implementations. The device elements and method elements describedherein may be interchangeable and used in or omitted from any of theexamples or implementations described herein.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements.

What is claimed is:
 1. A method of color error correction for asegmented LED array, the method comprising: (a) calculating a targetluminance for LED segments in a segmented LED array based on an initialluminance pattern; (b) determining a luminance ratio based on the targetluminance, the luminance ratio defined as a ratio of a primary luminancevalue of the primary LED segment to a secondary luminance value of theat least one adjacent LED segment; (c) comparing the luminance ratio toa predefined threshold ratio, and (i) if the luminance ratio is greaterthan or equal to the predefined ratio, then the secondary luminancevalue of the at least one adjacent LED segment is maintained, or (ii) ifthe luminance ratio is less than the predefined ratio, then thesecondary luminance value of the at least one adjacent LED segment isincreased.
 2. The method of claim 1, wherein the secondary luminancevalue of the at least one adjacent LED segment is increased in step(c)(i) until the luminance ratio equals the predefined threshold ratio.3. The method of claim 1, wherein the predefined threshold ratio is atleast 3% and less than 5%.
 4. The method of claim 1, wherein thepredefined threshold ratio is 4%.
 5. The method of claim 1, wherein thesegmented LED array includes a phosphor layer and a sapphire layer. 6.The method of claim 1, wherein the segmented LED array is a 2×1 LEDarray.
 7. The method of claim 1, wherein the segmented LED array is a3×3 LED array.
 8. The method of claim 1, wherein the at least oneadjacent LED segment includes at least one directly adjacent LED segmentand at least one diagonally adjacent LED segment, and the secondaryluminance value of the at least one diagonally adjacent LED segment is40-60% of the secondary luminance value of the at least one directlyadjacent LED segment.
 9. The method of claim 1, wherein an adaptiveflash process is performed during step (a).
 10. A system for color errorcorrection of a segmented LED array, the system comprising: a userinterface configured to detect a luminance pattern; a segmented LEDarray including individually controllable LED segments; a CPU configuredto receive the luminance pattern and a predefined threshold ratio, theCPU is configured to compare the predefined threshold ratio to aluminance ratio, the luminance ratio is based on the luminance patternand defined as a ratio of a primary luminance value of the primary LEDsegment compared to a secondary luminance value of the at least oneadjacent LED segment; and a driver configured to selectively illuminateindividual LED segments in the segmented LED array based on a comparisonof the predefined threshold ratio to the luminance ratio.
 11. The systemof claim 10, wherein the CPU sends input signals to the driver toincrease the secondary luminance value of the at least one adjacent LEDsegment until the luminance ratio equals the predefined threshold ratio.12. The system of claim 10, wherein the system dynamically determinesthe predefined threshold ratio.
 13. The system of claim 10, wherein thesystem is pre-programmed with the predefined threshold ratio, and thepredefined threshold ratio is selected based on at least onecharacteristic of the segmented LED array.
 14. The system of claim 10,wherein the secondary luminance value of the at least one adjacent LEDsegment is at least 3% of the primary luminance value of the primary LEDsegment, and the secondary luminance value of the at least one adjacentLED segment is less than 5% of the primary luminance value of theprimary LED segment.
 15. The system of claim 10, wherein the at leastone adjacent LED segment includes at least one directly adjacent LEDsegment and at least one diagonally adjacent LED segment, and thesecondary luminance value of the at least one diagonally adjacent LEDsegment is 40-60% of the secondary luminance value of the at least onedirectly adjacent LED segment.
 16. The system of claim 10, wherein thesegmented LED array includes a phosphor layer and a sapphire layer.